"Google has revealed that it has no plans to develop dedicated apps for Windows 8 or Windows Phone 8 for its business app products such as Gmail or Drive." Product management director for Google Apps, Clay Bavor, told V3 that Google "will go where the users are but they are not on Windows Phone or Windows 8". Ouch - but for now, hard to argue with.

You nailed it: The vast majority of people ... that STILL is on Windows. That number is shrinking very fast. One of the reasons is that they are forced to use what Microsoft throws at them. Luckily they have choice today and can and in a lot of cases just switch to alternates like Android, iOS, OSX.